When we were in Switz at Easter, many of our neighbouring German and Swiss vanners used a raised flooring in their porch awnings. Basically it was made of lightweight plastic/PVC/rubber mats which laid on top of an aluminium frame of about 6-9" depth. Great idea for muddy pitches, and no damage to the grass underneath. I've not seen anything like it in the UK - anybody know where you can get them?